In a gas turbine engine, there are fluid pressure variations between axially adjacent zones, such as adjacent zones through which the turbine shaft passes, with resulting leakage of fluid, e.g., air and/or other gases, between the zones. In particular, there is typically leakage at clearances between stationary and rotating parts of a turbine engine wherein a leakage flow occurs from a higher pressure zone to a lower pressure zone across the clearance between the rotating part and the stationary part. In order to improve the thermodynamic efficiency of the engine, the leakage flow needs to reduced or minimized, such as by means of a seal provided in the annular space between the two relatively moving parts.
A seal for limiting leakage across the annular space may comprise a leaf seal. Leaf seals generally comprise a plurality of seal strips mounted to a carrier member and packed closely together in the circumferential direction. The flexible strips may bend in the circumferential direction, but exhibit a high resistance to bending in the axial direction, ensuring that the flexible strips will continue to be positioned closely adjacent to the rotating shaft even in the presence of high pressure differentials between the axially adjacent zones.